Method for charging storage batteries



Patented May 5, 1953 METHOD FOR CHARGING STORAGE nA'r'rERIEs Thomas L. Kendall, Clifford B. Bodenhafer, and

. Boy I. Plummet, Muncie, Ind., assignors to General Motors Corporation, Detroit, a ermrefi n of De a Application November 24, 1950, Serial No. 197,494

Claims. (Cl. 320-24) 1 This invention relates to storage batteries and is primarily concerned with processes for charging storage batteries.

It is a basic object of the invention to provide Another object of the invention is to provide a method forcharging storage batteries wherein the charge'rate is maintained as high as possible while controlling the maximum temperature of a new and improved charging pocess for Faure 5 the battery, whereby excessive gassing is elimstorage batteries wherein the period required to inated and the battery is charged ina shorter charge the battery is markedly reduced. time period than was heretofore possible.

It is a further object of the present invention Further objects and advantages of the present to provide a method for charging storage batterinvention will be apparent from the following deies wherein a high charge rate is utilized whereby scription, reference being had to the accompanythe period of time required to fully charge the ing drawing which shows graphically the chargbattery is greatly reduced, V ing procedure disclosed herein,

In carrying out the above objects, it is still a We have found that the charging rate input further object to provide a method for charging to a storage battery is controlled to a major destorage batteries of the Faure type wherein the gree by'the gassing tendency of the battery. This charging rate is maintained as high as possible gassing tendency is, in turn, controlled to a major compatible with gassing and temperature of the degree by the temperature of the electrolyte. To battery. this end we have discovered that batteries can be In carrying out the above object, it is a further charged very rapidly if temperature control of object to limit the battery temperature to a maxithe electrolyte is maintained whereby gassing is mum of 200 F. or below whereby gassing is conminimized and in this manner, a considerably trolled and wherein a fast charge is obtained. higher charging rate may be used in connection A still further object of the invention is to prowith batteries charged under these controls. vide a method for chargin batteries wherein the We have further found that if a break is ohbattery is charged to between one-third to twotained during the charging period, lead sulphate thirds and preferably one-half its full charge at crystals precipitate on the positive and negative as high a rate as possible without exceeding 9. plates and form nuclei for further growth of crysmaximum temperature of 200 F. The charge tals, which action vcreates a more desirable plate rate is then reduced sufficiently to permit cooling and further permits continued high charge rates of the battery to within about of the ambient 30 to be used due to the fact that the battery cools temperature and simultaneously cause a precipioff during this break or rest period. tation of lead sulphate crystals on the positive In essence, our invention is directed to charand negative plates. The battery is then again ing a battery at as high a rate as possible comcharged at as high a rate as possible while mainpatible with the temperature thereof and attend taining the maximum temperature thereof at 159 and gassing to bring the charge within the battery F. or less until the battery is fully charged. to from one-third to two-thirds its ,iull charge,

In carrying out the above object, it is a further after which the battery is rested during .a period object of the invention, in some cases, to reduce (when no charge is induced therein or when a very the charge rate to zero during the cooling off pereduced charge rate is being used. This rest period. riod extends for a time sufiicient to cause the bat- Another object of the invention is to provide a tery to cool considerably, for example, during the charging method for storage batteries of the lead first period the temperature of the battery should plate type wherein three periods are utilized. be maintained at 200 F (for ambient tempera- The first period provides a charge of from one- 'tures of about F.) or stated differently, from third to two-thirds and preferably one-half the 45 to maximum above the ambient ten-ifull charge of the battery at as high a rate as perature. During the rest period, the electrolyte possible while maintaining the temperature of the should be permitted to cool to a temperature of battery to between 100 and 120 F, about amfrom 20 to 40 above the ambient temperature bient temperature. The second period provides whereupon charging is again resumed at a high cooling e ry to from 20 to 40 above am.- 59 rate of charge compatible with the temperature bient temperature and the third period provides and with the gassing wherein the temperature of charging the battery at as high a rate as possible the electrolyte is controlled to a maximum temwhile maintaining the maximum temperature perature of from 50 to above the mbi nt thereof to from 50* to 90 above ambient tempertemperature until a full char e is obtained. ature until the battery is fully charged. :56 'lhe temperature control figures are easily maintained through control of the current used in the charging process. The magnitude of the current, that is, the amperes per square inch of positive plate area is not important here providing the temperature restrictions are maintained audit will be found that very high charge rates may beutilized when the temperature of the battery is carefully controlled. For example, we have found that lowering of the ambient temperature permits the use of higher charge. rates under otherwise similar conditions. This.

may be accomplished by fluid circulation, such" as induced ventilation, by refrigeration, etc., and

in each case as the ambient temperature goes down, the charge rate may be increased to a point where the maximum stated temperatures within the battery are obtained. Thus it is possible to fully charge a battery in very short periods of time, for example, from 16 to 22 hours, which short periods have hitherto been unheard of. v

For illustrative purposes only, the following figures are given to show one charging pattern with a l5-plate battery of automotive type having approximately 350 square inches of positive plate area. The battery is initially charged with a 25 ampere input for six hours at which point it will be found that the temperature of the battery has reached a maximum of about 170 with a 70 ambient temperature. is rested for about four hours whereupon the temperature thereof has dropped to about 114 F., then a 20 ampere charge is used for seven hours which increases the temperature of the battery to about 150 F. and finally a tenampere charge is used for five hours which causes a reduction in temperature to 117 F. within the battery. In this example, sulphuric acid having a starting gravity of 1.175 to 1.225 is preferred although starting gravities of. 1.050 to 1.300 may be used if the temperature of the electrolyte is properly controlled through control ,of the charge rate, ambient temperature and the like.

A chart showing counter E. M. F. and temperature conditions during each hour of, the above' charge is as follows:

. Charge Hours 0. E. M. F. Temp. rate, amp.

7. 114 20 7. 9 H6 20 8. 0 122 20 8. O 130 20 8 O 138 20 8. 0 142 20 8. 0 148 20 8. 0 149 20 7. 6 13S 7. 8 129 10 7. 8 125 10 7. 8 120 10 7. 8 117 10 Another specific example of fast charging of a storage battery with similar characteristics to these set forth above is; 25 to 35 ampere charge for four hours, a reduction in the charge to from 15 to amperes for two hours, a reduction in charge to from two to six amperes during the rest period for about four hours, a 20 to ampere charge for from six to seven hours and The battery finally aten to fifteen ampere charge for from four to five hours. It is apparent that through out this charging procedure, the ambient temperatures must be relatively low if the higher end of the charge rate ranges are to be used and in all cases the temperature limitations set forth herein should be maintained.

It is similarly possible to charge a battery for five hours at 35 amperes, cool the battery either with or without a reduced charge being induced therein to a temperature of about 20 to 40 above the ambient temperature and then fast charge the battery under low ambient temperature conditions for ten hours at a 25 ampere charge wherein the control of temperature is maintained at all times to a maximum of 120 F. above ambient temperature during the first period, a maximum of about 40 F. above ambient temperature at the end of the rest period and a maximum of about F. above ambient temperature during the final charging period.

The counter E. M. F. within the battery varies substantially inversely with the temperature while the temperature varies directly with the rate of charge and it is therefore necessary to balance these figures for best charging conditions. Since the temperature per se is the common factor, it is best to control this figure by raising or lowering the charge rate to maintain the optimum conditions wherein the specific maximum temperature stated here should be maintained. In all cases, the charging rate is dependent on the temperature which limits the gassing and therefore it is impossible to state the specific rate without knowledge of ambient temperature conditions, however, the examples set forth herein show the wide variation which may be practiced, in all cases controlling the maximum temperatures during the specific charge periods.

The rest period with or without a low charge is important both from a cooling angle and from a conditioning standpoint wherein precipitation of lead sulphate crystals creates a desirable condition within the battery. From the foregoing it will be apparent that we have discovered a method for fast charging batteries wherein the application of a few simple controls permits reduction in the period of time normally used to charge a battery control of the counter E. M. F., proper formation of the positive plate paste and likewise prevent overheating of the battery with the many deleterious effects resulting therefrom. In all cases, the temperature differential is the important factor during the specific charging procedure.

While the embodiment of the present invention as herein disclosed, constitutes a preferred form,

electrolyte to a maximum of not to exceed F.

above the ambient temperature, reducing the charge on the battery to a point sufiicient to permit the battery electrolyte to cool to a least 40 F. above the ambient temperature and simultaneously to precipitate crystals of lead sulphate on the positive and negative plates, and then charging the battery at a rate further reduced until fully charged while simultaneously limiting the temperature of the electrolyte to a maximum of 90 F. above the ambientv temperature, whereby the battery receives a full charge without excessive gassing and in a relatively short time.

2. In a method for the fast charging of batteries of the pasted lead plate type, the steps comprising; charging the battery until approximately a one-half charge is obtained at a rate suflicient to bring the temperature of the battery to a maximum of not over 120 F. above the ambient temperature, cooling the battery to approximately 40 F. above ambient temperature, and then again raising the temperature of the battery to approximately 90 F. above ambient temperature through an induced charge therein less than the initial charge until the battery is fully charged.

3. In a method for the fast charging of storage batteries of the pasted lead plate type wherein a -p1ate battery includes about 350 square inches of positive plate area, the steps comprising; charging the battery at about a ampere rate for about six hours, resting the battery for approximately four hours, charging the battery at a reduced rate of about 20 amperes for seven hours and then further reducing the charge rate to about 10 amperes for about five hours whereupon the battery is fully charged and the positive plates are properly formed.

4. In a method for the fast charging of storage batteries of pasted lead plate type, the steps comprising; inducing a charge therein as high as possible while simultaneously maintaining the battery at not over 120 F. above ambient temperature maximum for a time sufiicient to bring the battery to approximiately one-half charge, reducing the initial charge sufiiciently to cause the battery to cool to a temperature of not less than 40 F. above the ambient temperature, and

then again charging the battery at a further reduced rate while maintaining a maximum temperature of F. above ambient temperature until the battery is fully charged.

5. In a method for the fast charging of storage batteries of the pasted lead plate type, the steps of; limiting the temperature of the battery to a maximum of F. above ambient temperature While inducing as high a charge as is possible into the battery through a period suiricient to cause the battery to become from one-third to twothirds fully charged, precipitating lead sulphate crystals on the positive and negative lead plates by cooling the battery to a temperature of not less than 40 F. above ambient temperature by resting the battery, and then further charging the battery at a rate less than the initial rate used while maintaining a maximum temperature of not more than 90 F. above the ambient temperature during the final charge period for bringing the battery to full charge.

THOMAS L. KENDALL. CLIFFORD B. BODENHAFER. ROY I. PLUMMER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,126,669 Wilson Jan. 20, 1915 1,224,986 Wilson May 8., 1917 1,287,259 Dixon Dec. 10, 1918 1,457,863 Strawmyer et al. June 5, 1923 1,602,559 Strawmyer Oct. 12, 1926 1,743,593 Broadfoot Jan. 14, 1930 1,743,594 Broadfoot Jan. 14, 1930 1,786,280 Woodbridge Dec. 23, 1930 2,070,541 Beetem Feb. 9, 1937 2,227,118 Amsden Dec. 31, 1940 2,354,877 Peters Aug. 1, 1944 

1. IN A METHOD FOR THE FAST CHARGING OF BATTERIES OF THE PASTED LEAD PLATE TYPE, THE STEPS COMPRISING; PASSING THE HIGHEST CHARGE CURRENT POSSIBLE THROUGH THE BATTERY FOR A TIME SUFFICIENT TO BRING THE CHARGE WITHIN THE BATTERY TO FROM ONE-THIRD TO TWO-THIRDS FULL CHARGE WHILE SIMULTANEOUSLY LIMITING THE TEMPERATURE OF THE BATTERY ELECTROLYTE TO A MAXIMUM OF NOT TO EXCEED 120* F. ABOVE THE AMBIENT TEMPERATURE, REDUCING THE CHARGE ON THE BATTERY TO A POINT SUFFICIENT TO PERMIT THE BATTERY ELECTROLYTE TO COOL AT LEAST 40* F. ABOVE THE AMBIENT TEMPERATURE AND SIMULTANEOUSLY TO PRECIPITATE CRYSTALS OF LEAD SULPHATE ON THE POSITIVE AND NEGATIVE PLATES, AND THEN CHARGING THE BATTERY AT A RATE FURTHER REDUCED. 